Method of making and filling a multi-chamber container

ABSTRACT

A container capable of containing components of a mixture in chambers separated by a peelable seal constructed from a multi-layer film. The multi-layer film has at least one layer of a RF-responsive material and an interior layer of non-RF responsive material. When the layers are subjected to RF energy, the RF-responsive layer heats the interior layers resulting in a bond in the form of a peelable seal between the interior layers. The peelable seal is capable of withstanding external pressures to the container, such as from dropping the container. The seal may be selectively opened to allow mixture of components contained therein.

This is a division of application Ser. No. 08/033,233, filed Mar. 16,1993.

BACKGROUND OF THE INVENTION

The present invention generally relates to flexible containers forhousing liquid products. More particularly, the present inventionrelates to multi-chamber containers having a selectively openable sealline between two chambers.

Flexible containers, constructed from plastic films, are commonly usedin the medical field for containing, inter alia, parenteral, enteral,and dialysis solutions. A great variety of such solutions can be housedand stored in such containers.

There are, however, a number of products that due to stability,compatibility, or other concerns must be stored in component parts inseparate containers and admixed before use. For example, amino acid anddextrose solutions require separate storage containers or compartments.These components, therefore, are stored separately and then mixed priorto use.

One of the disadvantages of storing components in separate containersand then mixing them together is that the mixing process can compromisesterility of the system. Additionally, this step creates a labor intenseprocess.

To deal with the disadvantages of separate containers, it is known toprovide multiple chamber containers having an interior including two ormore chambers. One way to create such a container is with a heat sealdividing the interior into two chambers. Such containers are disclosed,for example, in U.S. Pat. Nos. 4,396,388; 4,770,295; 3,950,158;4,000,996; and 4,226,330.

It is known to use frangible valves between the heat seal to allow forselective communication and mixing of the two components stored in theseparate chambers. See, for example, U.S. Pat. No. 4,396,488.

However, such a structure--frangible valves--may not be desirable for anumber of reasons, including, inter alia, cost. An alternative tofrangible valves is disclosed in U.S. Pat. Nos. 3,950,158, 4,000,996 and4,226,330, where multiple chamber containers are disclosed with a lineof weakness, such as a score line, which breaks upon the application ofpressure.

In U. S. Pat. No. 4,770,295, a selectively openable seal line ispositioned between two sheets of flexible thermoplastic material. Theseal line is resistant to unintentional opening forces, but opens uponapplication of a specific force. The seal line may be employed invarious containers, including a two chamber container for the separatestorage and selective mixing of two medical substances. The containerincludes two sheets forming the exterior of the container and an innerdiaphragm sheet between the outer sheets. One selectively openable sealis disposed between one of the outer sheets and the diaphragm sheet. Apermanent line of securement is preferably included between the exteriorsheet and the diaphragm sheet extending substantially parallel to andco-extensive with the openable seal line.

In addition, tear tabs or tear strips for plastic packaging are alsoknown, such as shown in U.S. Pat. No. 2,991,000. Such tear tabs provideaccess to the contents of the container. However, a disadvantage withthese containers is that they also involve the use of relativelycomplicated seal structures. U.S. Pat. No. 3,983,994 discloses a sealbroken by pulling upon tabs located outside of the container.

Another issue that must be considered in constructing containers for themedical industry is that the solutions, and therefore the containers,often require sterilization after manufacture of the container andsolution. Typically, the products are sterilized by steam sterilization,or autoclaving. Autoclave sterilization can alter the thermal propertiesof the film used to form the container and seal between chambers of thecontainer.

Of course, it is desirable to provide a multichamber container with aseal between the chambers that is capable of withstanding externalstresses. Such stresses include pressure that may be applied to one ormore of the chambers from, for example, squeezing thereof, or accidentaldropping of the bag. Therefore, the seal must be sufficiently strong.

However, a difficulty in creating the seal is that the strength of theseal typically increases during sterilization. As a result, a seal maybe too strong after the sterilization process making it difficult toseparate the seal to combine the components within the chambers.

A need, therefore, exists for a flexible container having chambersseparated by a frangible or separable seal that overcomes thedisadvantages of the prior art.

SUMMARY OF THE INVENTION

The present invention provides a flexible container defining a pluralityof internal compartments separated by a seal. At least the seal regionis constructed from a film that comprises at least two layers, one ofwhich is RF-responsive and the other layer, the inner layer, beingnon-RF responsive. The RF-responsive layer, in response to RF energy,heats the non-RF responsive interior layer to form a peelable seal thatis defined by a bonding between the non-RF responsive layers that definean interior of the container.

Preferably, the non-RF responsive layer is an alloy of at least twomaterials that have differing melting points. To create the seal, thelayer is heated to a temperature wherein only one of the materialsmelts.

In an embodiment, the seal layer is an alloy ofstyrene-ethylene-butyl-styrene (SEBS) and ethylene propylene copolymer.Accordingly, when the seal is being created, the inner layer is heatedby the RF-responsive layer to a temperature wherein the SEBS melts andflows into a corresponding inner layer. However, the temperature is notgreat enough to cause the ethylene propylene copolymer to melt. A sealis created between the two inner layers due to the melting of the SEBS.This creates a strong seal between the two inner layers that can be"peeled" when desired using a force normal thereto.

The present invention also provides a method for making a multi-chambercontainer comprising the steps of providing a web of plastic film havinga first non-RF responsive layer and a second RF-responsive layer;sealing opposing edges of the web of film to create an interior defined,at least in part, by the inner layers; and creating an inner seal,defining at least two chambers, by applying RF energy and causing aportion of the inner layers to seal to themselves.

An advantage of the present invention is to provide a container having apeelable seal capable of withstanding external stresses due to pressureapplied to the container or to individual chambers of the container.

A further advantage of the present invention is to provide a containerhaving a peelable seal that strengthens during sterilization yet iscapable of being easily opened by healthcare personnel.

Moreover, an advantage of the present invention is to provide acontainer having a peelable seal which is uniform in strength across thelength of the seal allowing for improved performance since theconcentration of stress is inside the seal area.

A still further advantage of the present invention is to provide acontainer having a peelable seal that readily separates when desired.

Another advantage of the present invention is to provide a containerhaving a peelable seal that is RF sealed rather than heat sealed.

A further advantage of the present invention is to provide a containerhaving a peelable seal which is formed with a seal bar that results in astrong, consistent seal.

A still further advantage of the present invention is to provide acontainer having a peelable seal separating chambers of the containerthereby requiring no special polymer alloys, intermediate zones orexternal devices in order to maintain a separation of solutions.

Moreover, another advantage of the present invention is to provide acontainer having a peelable seal which stretches when selectively openedrather than fractures.

Yet another advantage of the present invention is to provide a containerhaving a peelable seal which is simple to manufacture using a minimalamount of material.

Another advantage of the present invention is to provide a container inwhich the solutions and/or products contained therein do not react withthe film of the container.

Additional features and advantages are described in, and will beapparent from, the detailed description of the presently preferredembodiments and from the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 of the present invention is a perspective view of a flexiblecontainer separated into two chambers by a seal line.

FIG. 2 is a cross-sectional view of an embodiment of the film used toconstruct the container of the present invention taken generally alongplane II--II of FIG. 1.

FIG. 3 is an end view of an embodiment of a die used to create the sealline of the container of the present invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

The present invention provides a multi-chambered container that can beused to house two products that are to be stored separately prior touse. Due to the unique seal structure, the two products can be easilymixed prior to use.

Referring to FIG. 1, a multi-chambered container 10 is generally shown.The container 10 includes two chambers 12 and 14 for the separatestorage of substances and/or solutions. A peelable seal 16 is providedbetween the chambers 12 and 14. Although in the embodiment illustrated,the container 10 includes two chambers 12 and 14, it should beappreciated that additional peelable seals may be included to divide thecontainer 10 into additional chambers.

The container 10 is formed from a flexible sheet of plastic. Thecontainer may be formed from two sheets of film that are heat sealedalong their edges. However, the container can be formed from a web offilm folded over and sealed along three sides. Pursuant to the presentinvention, the container is formed from a multi-layer film discussedbelow.

In the illustrated embodiment as shown in FIG. 2, two sheets of film areused. A first sheet 18 and a second sheet 20 are sealed about theperiphery 22 of the container 10 by, for example, heat sealing. Thepeelable seal 16, described more fully below, is provided between thesheets 18 and 20 to form the chambers 12 and 14.

In the preferred embodiment illustrated in FIG. 1, at a top end 24 ofthe container 10 is a tubular port 26. The port 26 providescommunication with the chamber 12 and can include a suitable membranecovering which can be pierced by, for example, a cannula or a spike ofan administration set so that additional substances and/or solutions canbe added to the chamber 12. The tubular port 26 allows the first chamber12 to be filled.

At a bottom end 28 of the container 10, in the illustrated embodiment,are three tubular ports 30, 32 and 34. One of the tubular ports 30, 32,or 34 allows the second chamber 14 to be filled with a liquid. Thetubular ports 30, 32 and 34 also allow the medical substances containedwithin the container 10 to be discharged to one or more patients.Similarly, the tubular ports 30, 32, and 34 allow medicaments to beinjected into the container.

The tubular ports 30, 32 and 34 are mounted in the container 10 tocommunicate with the container 10 via the chamber 14. The ports 30, 32and 34 can include a membrane that is pierced by, for example, a cannulaor a spike of an administration set for delivery of the contents of thecontainer 10 through the administration set to the patient. Of course,more or less than three ports can be used.

Preferably, at the top end 24 of the container 10 is an area whichincludes a hanger hole 36 for supporting the container 10 by, forexample, a hook (not shown).

In FIG. 2, the sheets 18 and 20 which form the container are illustratedin cross-sectional view. Specifically, the seal 16 is illustrated at thejunction of the sheet 18 with the sheet 20. The seal 16 is formed suchthat no communication between the chambers 12 and 14 is provided untilthe seal 16 is broken. Rupturing of the peelable seal 16 serves toprovide communication between the chambers 12 and 14 allowing a mixingof the substances stored therein.

The sheets 18 and 20 are flexible and are preferably made of the samematerials. In the illustrated embodiment, the first sheet 18 includes afirst layer 40 forming an outer surface or abuse layer of the container10. The first layer 40 may be, for example, a thermoplastic materialsuch as PCCE. A typical thickness of the first layer 40, in a preferredembodiment, is approximately 0.55 mil but may vary, for example, between0.40 mil and 0.70 mil.

A tie layer 42 can be provided to provide a binding layer between theoutside layer 40 and a second layer 44 of the sheet 18 which isRF-responsive. Although in a preferred embodiment, the tie layer 42 hasa thickness of approximately 0.4 mils, the tie layer 42 may, however,have a varied thickness, for example, between 0.25 mils and 0.55 mils.The tie layer 42 can be a thermoplastic material such as ethyl vinylacetate (EVA) modified with malic anhydride.

The second layer 44 is an RF-responsive layer that, as discussed below,cooperates with a sealing or inner layer 46 to create the seal. Thesecond layer 44 can be any RF-responsive material. In a preferredembodiment, the RF-responsive material is an ethyl vinyl acetate (EVA).It has been found that a layer thickness of approximately 6.2 milsfunctions satisfactorily. However, the second layer 44 can have a variedthickness of between, for example, at least 5.75 mils and 6.75 mils.

The sealing layer 46 is made of a non-RF responsive material.Preferably, the non-RF responsive layer includes at least two materialshaving different melting points. In an embodiment, the non-RF-responsivelayer is an alloy of styrene-ethylene-butyl-styrene (SEBS) for example,Kraton®, and ethylene polypropylene copolymer. It has been found that ifthe sealing layer has a thickness of approximately 1.6 mils it functionssatisfactorily. However, the thickness may vary, for example, between1.40 mils and 1.80 mils.

The sealing layer 46 is adjacent the solution side of the container suchthat when the seal 16 is ruptured, communication is provided between thechambers 12 and 14. As noted above, the four-layer film illustrated inFIG. 2 has at least one RF-responsive layer 44 and one non-RF responsivelayer 46. A RF field heats a seal bar 62 (described hereinafter withreference to FIG. 3) which heats the RF-responsive layer 44 which, inturn, heats the non-RF responsive layer 46 to soften the layer 46, butnot liquify same. A resulting cohesive bond develops from contactbetween the non-RF responsive layer 46 of the sheet 18 and acorresponding non-RF responsive layer 56 of the sheet 20, but fusionbetween the layers, which can cause permanent bonding, does not occur.

As previously indicated, the container 10 can be formed by folding asingle web, such as the sheet 18, or alternatively, the sheet 20 can befurther provided in addition to the sheet 18. In the preferredembodiment, the sheet 20 is a four-layer film in which layers 50, 52, 54and 56 of the sheet 20 substantially correspond to the layers 40, 42, 44and 46 of the sheet 18, respectively. As a result, the sealing layer 56of the sheet 20 forms a cohesive bond with the sealing layer 46 of thesheet 18. The cohesive bond formed is the peelable seal 16.

The peelable seal 16 is formed by radio frequency welding of the twosheets 18 and 20. As illustrated in FIG. 3, a die 60 is generally shown.The die 60 includes the seal bar 62 which is formed to projectsubstantially perpendicularly to a base 64 on which the seal bar 62 isintegrally mounted. The base 64 can be further secured to manufacturingcomponents (not shown) by fasteners (not shown) inserted through holes66 in the base 64. The seal bar 62 of the die 60 is used to form thepeelable seal 16 wherein the seal bar 62 can be energized using RFenergy.

The seal bar 62, as illustrated, has a substantially equal width,designated as "x" in FIG. 3, of, in the preferred embodiment,approximately 3/8 inches. The seal bar 62 further includes radiusedcorners 68 so as to create a strong, consistent seal 16 across thecontainer 10. In the preferred embodiment illustrated, the radialdimension is 1/16", generally designated as "r". The peelable seal 16formed using the seal bar 62 of the present invention results in a bondwhich is less likely to break due to external forces exerted thereon.

By way of example, and not limitation, an example of how the peel sealis created will be given. In a preferred embodiment, the inner layerincludes SEBS and ethylene polypropylene. SEBS has a melting point ofapproximately 127° C. and ethylene polypropylene approximately 140° C.The die, illustrated in FIG. 3, is initially heated to a temperature of50° C. and urged against the container in a position to create thedesired seal. The die is then energized with sufficient RF energy toreach a temperature of between 128° C. and 131° C. This creates the peelseal.

It should be noted that in creating the side seals, a temperature ofgreater than 140° C. is used. This creates complete fusion of the sideseal area.

It should be appreciated that fewer layers for each of the sheets 18 and20 than the four-layer film described with reference to FIG. 2 can beused to create the peelable seal 16 of the present invention. At aminimum, two layers are required, one layer being RF-responsive and theother layer being non-RF responsive. Reliability and strengthening ofthe peelable seal 16 may be further enhanced by using corona treatmentor an extrusion process.

The peelable seal 16 is preferably formed to withstand external pressureto one or both chambers 12 and 14 of the container. Furthermore, thepeelable seal 16 is capable of withstanding pressure exerted by droppingthe container 10 either on its side or if it is dropped flat.Preferably, the peelable seal 16 can withstand rupture from a drop of upto six feet.

Post-sterilization of the chambers 12 and 14 of the container 10substantially increases the pressure which the peelable seal 16 iscapable of withstanding before rupture. More specifically, sterilizationcan increase seal strength between 40 and 80 percent.

It should be understood that various changes and modifications to thepreferred embodiments described herein will be apparent to those skilledin the art. Such changes and modifications can be made without departingfrom the spirit and scope of the present invention and withoutdiminishing its attendant advantages. It is, therefore, intended thatsuch changes and modifications be covered by the appended claims.

We claim:
 1. A method for making a multi-chamber container, the methodcomprising the steps of:providing a web of plastic film having a firstcontinuously formed non-RF-responsive layer and a second continuouslyformed non-RF-responsive layer wherein the first layer and the secondlayer are continuously bonded to each other; sealing opposing edges ofthe web of film to create an interior defined, at least in part, by aninner layer of the film; and creating an inner seal defining at leasttwo chambers by applying RF energy and causing a portion of opposinginner layers of the film to seal themselves.
 2. The method of claim 1further comprising the step of:applying only sufficient RF energy tocause only one of two alloys that comprise the first non-RF-responsivelayer to melt.
 3. The method of claim 1 further comprising the stepof:filling at least one chamber with a medical solution.
 4. The methodof claim 1 wherein the first non-RF-responsive layer includes SEBS andethylene propylene copolymer.
 5. The method of claim 1 wherein the filmincludes at least three layers.
 6. The method of claim 1 wherein theRF-responsive layer includes ethylene vinyl acetate.
 7. The method ofclaim 1 further comprising the step of:providing the container with atleast two ports.
 8. The method of claim 1 further comprising the stepof:filling a first chamber and a second chamber in the interior withdifferent medical solutions.